A method and an apparatus are proposed hereafter for the production, purification, or conversion of dispersed materials in plasma. The method and the device allow an improved process of conversion of dispersed materials under plasma conditions. Dispersed materials are understood as materials which are finely pulverized, the individual particles of the dispersed materials being able to have greatly varying shapes and sizes. For example, the particles may be spherical or elongate, needle-shaped, etc. In many cases, these are mineral materials such as silicon, which is brought into a high-purity state in this way or is obtained by conversion from quartz inside the apparatus by the action of the plasma. Using the proposed method and the device, materials of this type may, for example, be produced in a chemical reaction, be purified of undesired admixtures, or be converted by bonding with other materials.
In known methods and apparatuses, a plasma-forming gas is introduced from above into a reaction chamber and ionized. A dispersed material is simultaneously introduced into the reaction chamber in the same direction, i.e., from top to bottom, so that the dispersed material is purified or converted by the action of the plasma. In all of these known methods and apparatuses, the treatment of the dispersed material is accordingly performed in accordance with the parallel flow principle. Methods and apparatuses which operate according to this principle are described, for example, in U.S. Pat. Nos. 4,379,777, 4,642,207, 4,853,250, 6,379,419, US 2003/0143153 A1, US 2005/0217421 A1, US 2007/0029291 A1, and US 2007/0130656 A1. In general, it is unavoidable in the known methods and apparatuses that a cooled inlet is used for introducing the dispersed material because of the high temperatures in the area of the plasma.
With suitable design, the mass losses of processed material as a result of material vaporization may be reduced and the power-technology characteristic values of the reactor may be improved by selective plasma processing of the material depending on the size of the particles reaching the reactor by the method described hereafter and the proposed apparatus for performing the method. In addition, embodiments of the described method and the apparatus offer an effective design, which is cost-effective in regard to the investment outlay, for removing the processed material and an increase of the continuous target operating time of the plasma reactor.